Composite bulky regenerated cellulose yarn



Sept. 17, 1963 R. WOODELL 3,103,732

COMPOSITE BULKY REGENERATED CELLULOSE YARN Filed Dec. 11. 1958 2Sheets-Sheet 1 INVENTOR RUDOLPH WOODELL ATTORNEY Sept. 17, 1963 R.WOODELL 3,103,732

COMPOSITE BULKY REGENERATED CELLULOSE YARN Filed Dec. 11. 1958 2Sheets-Sheet 2 FIG. 2-

INVENTOR. Rvpol. PH weave LL.

BYRMJIKQ# United States Patent 3,103,732 CGMPOSITE BULKY REGENERATEDCELLULUSE YARN Rudolph Woodeli, Kinston, N.C., assignor, by mesneassignments, to Beaunit Corporation, a corporation of New York FiledDec. 11, 1958, Ser. No. 779,622 4 (Ilaims. (CI. 28-81) This inventionrelates to a new and useful bulky continuous filament yarn and a processfor its production.

Although artificial fibers are produced most easily as continuousfilaments, conventional continuous filament yarns because of theirextreme uniformity and lack of discontinuities are much denser thantheir staple counterparts. The filaments lie close together in the yarn,and adjacent strands of continuous filament yarn in fabrics are closelyand evenly spaced. Fabrics made from conventional continuous filamentyarns are therefore lacking in lightness and covering efiectiveness aswell as in interesting decorative surface effects which are commonlyachieved with yarn spun from staple fibers.

One method of increasing the bulkiness of continuous filament yarns isto spin under conditions such that the yarn develops a crimp whenexposed to a swelling agent in a relaxed condition as described byNicoll in US. 2,515,834. While crimped yarns made in accordance with theabove patent have proved highly useful, they suffer from thedisadvantage that in certain end uses, such as in plain weave, wovenfabrics 'for draperies and upholstery where the yarn is subjected to acertain amount of tension during the textile handling and weavingoperations, the crimp is removed.

It is accordingly an object of the present invention to provide acrimped yarn which may be subjected to tension without removal of thecrimp.

Another object is to provide a process to produce the yarn of thepresent invention.

Other objects will become apparent from the examples and discussions tofollow.

In accordance with the present invention a yarn is provided comprising aplurality of crimped (multiple component) filaments having combinedtherewith a plurality of substantially straight, uncrimped (singlecomponent) filaments which are grouped together and adhere to oneanother sufiiciently to form a coherent tension supporting strand, thecrimped filaments constituting a majority of the filaments.

The yarn is produced by supplying at least two viscose-s to a commonspinneret at substantially the same volume rate, extruding the viscosesthrough the spinneret into a coagulating and regenerating bath, one ofthe viscoses containing a coagulation modifier and having a higher saltindex than the other viscose, the other viscose containing nocoagulation modifier, the viscose containing the coagulation modifierbeing extruded through part of the spinneret holes (producinguncrimpable single component filaments) and both the viscoses beingextruded simultaneously through the remaining holes (producing crimpablemulticomponent filaments) the coagulating bath containing from about 8to 12% sulfuric acid, from about 3 to about 15% zinc sulfate and fromabout to. about 24% sodium sulfate, stretching the yarn and thereafterpermitting the yarn to relax.

In order that the tension-supporting strand have sufiicient strength, itmust include a substantial number of filaments. The exact numberrequired will depend on the filament denier, the total denier of theyarn and other factors. However, in general, it is desirable that thisstrand consist of about 10 to 40% of the total filaments in the yarns.

In a preferred embodiment the uncrimped filaments are grouped togetherin the interior of the filament bundle.

FIGURE 1 is a sectional elevation of a spinneret positioned upon anadapter suitable for preparing the yarn of the present invention.

FIGURES 2, 3, and 4 are cross-sectional views of the filaments occurringin the yarn of the present invention, 500 times actual size, made fromphotomicrographs. FIGURE 2 shows the mixture of uncrimped singlecomponent filaments and crimped multiple component filaments present inthe yarn. FIGURE 3 shows a number of uncrimped single componentfilaments adhering to one another at a few points, and FIGURE 4 shows anumber of crimpled multiple component filaments, in each case separatedfrom the yarn shown in FIGURE 2.

The following example is cited to illustrate the invention. It is notintended to limit it in any manner.

Example Two viscoses, designated hereinafter as viscoses A and B, areprepared. Viscose A, containing 6.55% by weight of recover-ablecellulose and 7.93% alkali calculated as sodium hydroxide, is preparedin the conventional manner using 40% carbon disulfide. Duringthe mixingoperation sufficient sodium N-methylcyclohexyldithiocarbamate is addedto give a concentration of 0.59% based on weight of the viscose. Theviscose is filtered, deaerated and ripened to a salt index of 15 and aviscosity of 47 poises. Viscose B is prepared in a similar fashionexcept that the recoverable cellulose content is 6.12% and the alkali5.14%. Viscose B is prepared with 30% carbon disulfide and the sodiumN-methylcyclohexyldithiocarbamate is omitted. Viscose B is filtered,deaerated and ripened to a salt index of 2.8 and a viscosity of 44poises. Viscoses A and B are then extruded through a common spinneret,as shown in FIGURE 1, the total rate of flow through the spinneret being77.5 grams per minute and the two viscoses being supplied to thespinneret at approximately the same rate of flow.

Referring to FIGURE 1 the apparatus employed comprises a spinneret '1containing holes of 0.008 inch diameter arranged as inner 2 and outer 3concentric circles. The said spinneret is positioned upon a viscoseseparator 4 by means of a threaded collar (not shown), the saidseparator having an outer circular channel 5 and an inner circularchannel 6, each of the said channels being concentric on central conduit7. A branch 8 of central conduit 7 feeds the outer circular channel. Anindependent conduit 9 feeds the inner circular channel. Viscose A isintroduced through independent conduit 9 while viscose B reaches thespinneret through branched conduits 7 and 8. Mixing of the viscosesoccurs just prior to extrusion from holes 2 and 3 except that since thefeeds are at the same rate of flow and since viscose A is supplied tothe adapter by a single conduit, whereas Viscose B is supplied by twoconduits, a localized high pressure is produced by the viscose A streamwith the result that viscose B is completely displaced from a number ofthe holes of the inner circle 2 and viscose A alone is extruded fromthese holes.

The viscoses are extruded into a coagulating and regenerating bathcontaining 11.0% sulfuric acid, 17.5% sodium sulfate and 9.5% zincsulfate, the bath being maintained at a temperature of 60 C. Thecoagulated filaments are led for a distance of 45 inches through thebath, then over a Y-guide to converge the filaments and for a furtherdistance of 396 inches through the bath where the yarn is confined bymeans of suitable roller guides. The yarn is stretched 40% in theprimary bath. The yarn is then passed for a distance of 160 inchesthrough a hot secondary bath containing 2.0% sulfuric acid, 3.9% sodiumsulfate and 2.1% zinc sulfate, the temperature of the bath being 95 C.The yarn is stretched 23% in the secondary bath by means of power drivenrollers. The yarn is then passed into a centrifugal spinning bucket inthe conventional manner and wound into a cake at a speed of 50 yards perminute.

The yarn is then purified, finished and dried in the conventionalmanner. The final yarn has an excellent crimp, the crimp being retainedwhen the yarn is placed under tension. This retention of the crimp undertension is found to be due to the fact that the filament bundle containsabout 25 filaments which are shorter, when straightened, than theremainder of the filaments. When the yarn is placed under tension, thesefilaments support the load and the other filaments remain in the crimpedcondition. It is found that a considerable number of these shortfilaments are stuck together at various points. When the short filamentsare embedded in wax, cross sections cut and examined microscopically inthe conventional manner, the filament cross sections have the sameappearance as those obtained by spinning viscose A alone (FIGURE 3). Onthe other hand, cross sections of the longer, crimped filaments show thepresence of both components (FIGURE 4).

The yarn, which has a denier of 2598 is woven into a plain-weave fiatfabric. The fabric has a bulky, spunlike appearance.

The essential modifications in conventional regenerated cellulose yarnproduction required in producing the yarn of this invention are (1) thesimultaneous extrusion of multiple viscoses which produce cellulosestructures of different shrinkage characteristics through part,preferably a majority, of the holes of the spinneret and (2) extradingthe viscose which produces the more shrinkable structure through theremaining holes. The difference in shrinkage of the two components inthe multiple com.- ponent filaments results in the crimping of thosefilaments while the higher shrinkage of the single component filamentsprovides the necessary tension-supporting strand.

In order that the uncrirnped filaments adhere to one anothersufficiently to form a coherent strand, the acidity of the bath must beregulated in accordance with other prevailing process conditions, andespecially in relation to the alkali content of the viscose, to achievethe desired effect. This may be accomplished for any given set ofconditions by spinning a small amount of yarn, examining the yarn, andif the uncrimped filaments do not adhere, i.e., they are not fusedtogether at numerous points along their length, adjusting the acidconcentration downwardly until these filaments do adhere. It isdesirable that the filaments adhere to one another at a sufiicientnumber of points to provide a single filament bundle which is notreadily separated.

The major factor in producing differences in shrinkage between filamentsmade from different viscoses is the difference in salt index whichreflects the maturity or ripeness of the viscose. In general, the higherthe index, the greater the shrinkage of the filaments. To produce thedesired effect of the present invention a difference in salt index of atleast 5 units is required. Preferably one of the viscoses has a saltindex above and the other viscose a salt index below 5. It is alsodesirable that the viscose having the higher salt index contain acoagulation modifier since this enhances the shrinkage of the filamentsand in addition leads to improved properties in the final yarn. Thepreferred modifiers are the amines described by Cox in U.S. 2,535,044,the dithiocarbamates described by Dietrich in U.S. 2,696,423, thequaternary ammonium compounds described by Cox in U.S. 2,536,014, thediamines described in British Patent 762,772, the ethers described inBritish Patent 741,728 and the polyethyleneoxides described in ItalianPatent 561,552. Other suitable m-odifiers are described in U.S. Patents2,777,775; 2,792,278; 2,792,279; 2,792,280; and 2,792,281; BritishPatents 723,435; 730,544; 748,147 and 765,905 and French Patents1,102,898 and 1,111,580.

Viscoses containing 5 to 9.5% recoverable cellulose and 4 to 8% alkali,calculated as sodium hydroxide, are suitable for the purposes of thisinvention. The viscoses are prepared in the conventional manner using 25to 60% carbon disulfide. Preferably, the viscose having the higher saltindex is prepared using a larger amount of carbon disulfide than theviscose having the lower salt index. It will be readily appreciated bythose skilled in the art that the amount of carbon disulfide requiredwill be dictated to a considerable degree by the salt index requirement.Thus, to obtain a salt index of 10 or higher, more than 30% carbondisulfide will be needed.

-As mentioned previously, the coagulating and regencrating bath shouldcontain from about 8 to about 12% sulfuric acid, from about 3 to about15% zinc sulfate, and from about 10 to about 24% sodium sulfate. Bathtemperatures in the range of from about 40 to about 70" C. aresatisfactory.

After extrusion, the filaments are led through the coagutlating andregenerating bath where they are confined by means of suitable rollerguides. The amount of bath travel required will depend on thecomposition and temperature of the coagulating bath, the composition ofthe viscose and other variables, but is easily adjusted by one skilledin the art. After leaving the primary coagulating and regenerating bath,the yarn is preferably passed through a hot secondary bath consisting ofhot water, dilute acid or diluted primary bath at a temperature of to C.

The yarn is stretched at least about 60% while passing through the bath.Where a secondary bath is used, the stretch may be concentrated in thisbath. However, it is usually preferable to apply part of the stretch inthe primary bath and part in the secondary bath.

After the yarn leaves the bath, it is wound into a cake in a centrifugalspinning bucket or wound on a bobbin and thereafter purified and driedin the conventional manner.

If the yarn is permitted to relax during the processing as in abucket-spun cake, then the yarn will be crimped without furthertreatment. However, if the yarn is wound on a bobbin under tension, itwill be necessary to place the yarn in water or some other swellingmedium in a relaxed state to permit it to crimp.

The yarns of this invention may be used wherever continuous filamentyarns are customarily employed. However, they are particularly suitablefor the production of fabrics in which a decorative surface effect isdesired as in draperies, friezes, and jacquards.

Many equivalent modifications of the present invention will be apparentto those skilled in the art from a reading of the above without adeparture from the inventive concept.

What is claimed is:

1. Composite, bulky, multi-filament yarn of regenerated cellulosepossessing crimp retention when subjected to tension during textilehandling and weaving operations consisting of crimped, heterogeneous,multiple component cellulose filaments together with tension supportingsubstantially straight, uncrirnped, single component cellulosefilaments, said crimped filaments consisting essentially of at least twocelluloses possessing different shrinkage characteristics, and saidtension supporting filaments being adhered to one another by cellulosefusion at a plurality of spaced points.

2. Composite, bulky, multi-filament yarn of regenerated cellulosepossessing crimp retention when subjected to tension during textilehandling and weaving operations as defined in claim 1 wherein thetension supporting filaments comprise from about 10% to about 40% of thetotal number of filaments in the yarn.

3. Composite, bulky, multi-filament yarn of regenerated cellulosepossessing crimp retention when subjected to tension during textilehandling and weaving operations as defined in claim .1 wherein thetension supporting filaments are grouped together in the interior of theyarn.

4. Composite, bulky, multi-filament yarn of regenerated cellulosepossessing crimp retention when subjected to tension during textilehandling and weaving operations as defined in claim 1 wherein thetension supporting filaments comprise from about 10% to about 40% of thetotal number of filaments in the yarn and are grouped together in theinterior thereof.

References Cited in the file of this patent UNITED STATES PATENTS1,993,847 Koch Mar. 12, 1935 2,234,763 Hoelkesamp Mar. 11, 19412,337,986 Fry Dec. 28, 1943 2,369,395 Heymann Feb. 13, 1945 2,386,173Kulp et a1. Oct. 2, 1945 2,399,260 Taylor Apr. 30, 1946 2,455,174 HittNov. 30, 1948 2,517,946 'Von Kohorn Aug. 8, 1950 2,623,266 Hemmi Dec.30, 1952 FOREIGN PATENTS 514,638 Great Britain Nov. 14, 1939

1. COMPOSITE, BULKY, MULI-FILAMENT YARN OF REGENERATED CELLULOSEPOSSESSING CRIMP RETENTION WHEN SUBJECTED TO TENSION DURING TEXTILEHANDLING AND WEAVING OPERATIONS CONSISTING OF CRIMPED, HETEROGENOUS,MULITIPLE COMPONENT CELLULOSE FILAMENTS TOGETHER WITH TENSION SUPPORTINGSUBSTANTIALLY STRIAGHT, UMCRIMPED, SINGLE COMPONENT CELLULOSE FILAMENTS,SAID CRIMPED FILAMENTS CONSISTING ESSENTIALLY OF AT LEAST TWO CELLULOSEPOSSESSING DIFFERENT SHRINKAGE CHARACTERISTICS, AND SAID TENSIONSUPPORTING FILAMENTS BEING ADHERED TO ONE ANOTHER BY CELLULOSE FUSION ATA PLURALITY OF SPACED POINTS.